Python 2.4.4 (#2, Jul 17 2007, 11:56:54) 
[GCC 4.1.3 20070629 (prerelease) (Debian 4.1.2-13)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> class A(object): pass
... 
>>> class B(object, A): pass
... 
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
TypeError: Error when calling the metaclass bases
    Cannot create a consistent method resolution
order (MRO) for bases object, A